Mounting for magnetostrictive driving units



April 12, 1949. H. N. HALL ETAL MOUNTING FOR MAGNETQSTRICTIVE DRIVINGUNITS Filed March 14, 1946 2 Sheets-Sheet 1 ATTORNEY April 12, 1949. H.N. HALL ETAL MOUNTING FOR MAGNETOSTRICTIVE DRIVING UNITS 2 Sheets-Sheet2 Filed March 14, 1946 ATTORNEY Patented Apr. 12, 1949 MOUNTING FORMAGNETOSTRICTIV E DRIVING UNITS Hubert N. Hall, deceased, late ofPrinceton, N. J by Ernestine May Hall, executrix, Princeton, N. 1., andJ. Guy Woodward, Princeton, N. 1., assignors to Radio Corporation ofAmerica, a

corporation of Delaware Application March 14, 1946, Serial No. 654,472

The present invention relates to transducers, and more particularly to amagnetostrictive signal translating device especially useful inunderwater signalling systems, echo range systems, and the like.

Conventional magnetostrictive projectors usually comprise a hollowcasing enclosed at one end by a vibratory magnetic diaphragm upon whicha plurality of magnetostrictive tubes are mounted. It is desirable thatall of the tubes shall have the same resonant frequency, and to this endcare is exercised to see that all of the tubes are of the same length.Notwithstanding this pre caution, however, the resonance will not be thesame, due to variation of mass in the mounting means. Anotherdisadvantage of conventional magnetostrictive projectors is that thediaphragm is usually about an inch thick. This makes it difiicult todrive all parts of the diaphragm in phase due to the inherent stiffness.These factors contribute to a relatively low efliciency. Furthermore,the relatively large clearance between each coil and its associatedmagnetostrictive tube contributes to the lowered efliciency of theprojector.

Some of the objects of the present invention are: to provide an improvedtransducer of the magnetostrictive signal translating type; to providean improved magnetostrictive transducer which will be free from theaforementioned and other difliculties inherent in prior art projectors;to provide an improved magnetostrictive transducer which has a very highefficiency; to provide an improved driving system for magnetostrictivetransducers which will drive all parts of the diaphragm with the samephase; to provide an improved mounting for the driving units of amagnetostrictive transducer; to provide a novel driving system formagnetostrictive transducer wherein the ratio of driving rod mass todiaphragm mass is increased, as compared to conventional system with areduction in Q performance; and to provide other improvements as willhereinafter appear.

In the accompanying drawings, Fig. 1 represents a fragmentary transversesection of a driv- 7 Claims. (Cl. 177-386) resents a plan of the unitshown in Fig. 5; Fig. 7

"represents a fragmental section of a modified form of mounting; andFig. 8 represents a plan of the unit of Fig, 7.

Referring to the drawings, the transducer comprises a diaphragm 10formed of relatively thin vibratory material, such as steel ormagnesium, and to which'the driving units are attached to havetelescopic relation with respect to a plurality of polarizing magnets 12supported by a flux distributing back plate l3. The magnets I2 and theplate l3 complete the magnetic circuit which carries the polarizingflux. Preferably, the magnets l2 are in the form of Alnico rods encasedin brass tubes 14. The driving units in the present instance, eachcomprise a driving rod l5 formed of nickel laminations bonded togetherwith a suitable bonding material, and axially disposed within andprojecting from a molded coil form l6 carrying the driving coil l'l. Asshown the form I6 is tapered and centered about the rod l5 so thatclearance is provided which prevents energy loss from rubbing of the twoparts. The coil form is so proportioned that the close fitting portionis at the node of the rod.

As shown, the form I6 has its supported end in the form of an invertedcup l8 through which the rod l5 passes to enter and be supported by theflanged square hub 20 of a base washer 2i preferably of thin sheetmetal. As assembled, the

' base washer 2| and the encircled end of the driving unit of a.transducer embodying one form of the present invention; Fig. 2represents a frag-,

mentary plan, partly broken away, of the same; Fig. 3 represents alongitudinal section of one driving unit. as illustrative of the novelmounting of all such units; Fig. 4 represents a plan of the unit shownin Fig. 3; Fig. 5 represents a longitudinal section of such a drivingunit illustrating a modified form of the mounting, Fig. 6 reping rodseat upon the face of the diaphragm W. The contact face of the washer 2!is machined smooth after silver soldering and is bonded to the diaphragml0 by Gelva, soft solder, or other suitable bonding material asindicated at 22, while the coil form I6 is cemented to the base washer2|, as indicated at 23.

In the form of the invention shown in Figs. 5 and 6, the coil form 24has its base portion formed at an inverted cup 25 provided withlaterally disposed side flanges 26 which seat upon the base washer 21and are respectively anchored thereto by providing slots 28 to receiveupstanding lugs 30 struck from the washer Z'l. These lugs 30 extendthrough the' respective slots 28 and project an appreciable distanceabove the plane of the top of the flanges 25. When the coil form 24 isassembled and seated upon the washer 2-1, the two lugs 30 are twisted tooverlie the flanges and thus unite -the parts together. As in the formof Figs. 3 and i, the end of the driving rod 3| is silver soldered intothe square hole ofthe washer hub32as indicated at 33.

In the form of driving unit mounting shown 3 in Figs. 7 and 8, thegeneral assembly of the driving rod and coil form are the same asheretofore described but in this instance was 34 are struck up from thewasher 35 in such spaced relation as to receive the flanges 38 of thecoil form between them, and by bending the lugs 3! over the respectiveflanges 30, the parts are firmly anchored. The washer 35 is bonded tothe diaphragm as in the other forms of the invention. It should be notedthat the washer 35 is preferably hexagonal in shape as this may allowthe rods to be oriented in a particular manner relative to the axis ofthe diaphragm.

From the foregoing it will be understood that the signal translatingunits comprising the washers, laminated rods, and the coils aredistributed in any desired manner over the entire surface of thediaphragm and as many of them may be used as will be found necessary. Itwill be understood, also, that each of the units can be removedindividually and separately tuned to a common resonant frequency, afterwhich all of the units can be remounted on the diaphragm In withtheassurance that they will remain tuned to this frequency.

A projector having a driving system of the type described above canemploy a diaphragm which is much thinner than conventional diaphragms(for example,'a diaphragm of about in thickness). Since the diaphragm isrelatively thin and is driven by units of the same resonant frequency,it is apparent that all parts of the diaphragm will move with the samephase. Moreover, by the novel mounting and assembly the load mass isreduced, resulting in an increase in the effectiveness of the internaldamping of the system as well as that of the external water load. anincrease in resonant frequency, and a reduction in Q. Furthermore, bythe use of individualwashers instead of a single sheet there is freedomfrom warping during the process of silver soldering. While the novelmounting is describedas associated with a magnesium diaphragm, theinvention is not limited in that respect as other thin diaphragms ofsteel, dural, hard rubber, or other material for which conventionalmounting methods are unsuitable can be used.

Having thus described our invention, we claim:

1. In a magnetostrictive transducer, a vibratory diaphragm, amagnetostrictive rod, a washer having an opening to seat the radiatingend of said rod, means for bonding said washer to said rod, means forbonding said washer to said diaphragm, a coil form encircling said rodand forming a circumferential seat, connecting means between said formand said washer, and a coil wound about said form and supported by saidseat.

2. In a m'agnetostrictive transducer, 2. vibratory diaphragm, amagnetostrlctive rod, a washer having an opening to seat the radiatingend of said rod, means for bonding said washer to said rod, means forbonding said washer to said diaphragm, a coil form having a boreencircling said rod, said bore outwardly tapering from a contact area ofminimum vibration of said rod to form a clearance to prevent rubbingcontact between the two members in rod vibration areas, connecting meansbetween said form and said washer, and a coil wound about said form.

3. In a magnetostrictlve transducer, a vibratory diaphragm, a laminatedmagnetostrictive rod. a washer having a hub dimensioned to receive anend of said rod as the sole support therefor, soldering means forbonding said rod and hub together, a coil form encircling said rod andhaving a cup-shaped base enclosing said hub. a coil wound on said formand seating on said base, and means for bonding said washer to saiddiaphragm.

4. In a magnetostrictive transducer, 9, vibratory diaphragm, a laminatedmagnetostrictive rod, a washer having a hub dimensioned to receive anend of said rod in contact relation, soidering means for bonding saidrod and hub together, a coil form encircling said rod and havs ingflanges seating on said washer, each of said flanges having a slottherethrough, lugs struck from said washer respectively located totraverse said slots and project therefrom to form anchoring means whenbent above said flanges, a coil wound upon said form, and means forbonding said washer to said diaphragm.

5. In a magnetostrictive transducer, a vibratory diaphragm, a laminatedmagnetostrictive rod, a washer having a hub dimensioned to receive anend of said rod in contact relation, soldering means for bonding saidrod and hub together, an internally tapered coil form each-- cling saidrod and having flanges seating on said washer, each of said flangeshaving a slot therethrough, lugs struck from said washer respectivelylocated to traverse said slots and project therefrom to form anchoringmeans when bent above said flanges, a coil wound upon said form, andmeans for bonding said washer to said diaphragm.

6. In a magnetostrictive transducer, a vibratory diaphragm, amagnetostrictive rod, a washer having a hub for seating an end of saidrod therein, a tubular coil form having a portion encircling said huband a portion tapering outwardly from a circumferential contact withsaid rod to form a clearance about said rod, a coil wound on saidtapered portion and seating upon said hub encircling part, meansconnecting said form and washer, and means bonding said washer to saiddiaphragm.

7. In a magnetostrictive transducer, a vibratory diaphragm, amagnetostrictive rod, means to attach the radiating end of said rod tosaid diaphragm as the sole rod support, a coil form encircling said rod,means to center said form about said rod, said means forming acircumferential area of contact with said rod only at an areasubstantially free from vibration, and a coil wound about said form.

ERNESTINE M. HALL, Executrim of the Estate of Hubert N. Hall,

Deceased.

J. GUY WOODWARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

